1. Field Of The Invention
This invention, generally, relates to a method and apparatus for displaying upon a viewing surface an image simulating a plane surface area illuminated by a light source and, more particularly, to an image simulating the ground area illuminated by a light source as viewed from an eye point within an aircraft
2. Description Of The Prior Art
This invention constitutes an improvement in the invention described and claimed in the U.S. Pat. No. 4,177,579 issued to Peters et al. on Dec. 11, 1979 and assigned to the same Assignee as the present invention.
Present day use of a simulator to train pilots and other aircraft personnel has become so widely accepted as to hardly warrant justification here. Such simulator apparatus today create a realistic aircraft environment that is designed to emphasize to each trainee that he is in and is operating an actual aircraft without leaving the ground.
To create this realism, the visual display system is a vitally important element. Many training judgments depend upon the trainee's response to a visual cue. During a simulation of an actual flight operation, a pilot, navigator, etc. will view the external environment through an aircraft window. For example, while taking off and while landing a pilot will scan the runway and will operate the controls of the aircraft to maneuver it properly.
Present day simulators utilize the viewing surface of a cathode ray tube, such as a raster-scanned television display, to simulate a window view. The external environment, seen by a trainee pilot as he looks out the window, is produced as the beam of the television cathode ray tube traces the raster across the viewing surface, and the scene produced on the viewing surface is generated most effectively by the above-identified U.S. Pat. No. 4,177,579.
Most actual aircraft and helicopters utilize landing lights and spot lights. These lights are located usually at some point distant from the pilot, on the wings or on another part of the aircraft, for example. Thc source of these lights also is adjustable usually by the pilot since they are important as a visual aid during night operation in order to provide ground illumination. Some aircraft, helicopters particularly, find spot lights extremely important where landing and taking off from confined areas are required. Simulators in the past have imposed an unrealistic burden on trainee's learning night operations by not providing an accurate simulation of an illuminated ground area, as well as both geographical references and altitude cues.
The unique characteristic produced by a directed beam of light in changing its shape on the illuminated ground area during changes in aircraft attitude and position was not provided prior to the invention discribed in the above-identified U.S. Pat. No. 4,177,579. As an aircraft changes its attitude and position, the area that is illuminated on the ground by the spot light will change its shape, since the light is intersecting the ground from different directions.
Therefore, with aircraft and other types of simulators being used extensively as training devices today, a need arises for simulators that have a high degree of realism, and it is of substantially equal importance that these simulators be constructed as economically as possible. Therefore, since proper training requires accurate visual systems, it becomes particularly important, in those simulators which develop simulated directed beams of light illuminating a plan surface, that a visual system be provided which has an accurate simulation of this significant and most important visual cue, and today, such simulation must be provided at the lowest possible cost.